My objective is to determine the mechanism of action of some common mutagens in a higher organism by examining the defects that the mutagens have produced. Utilizing the Adh/alcohol dehydrogenase system in Drosophila, my laboratory will analyze the alcohol dehydrogenase-like proteins found in Adh-negative strains for amino acid substitutions generated by these mutagens. From the genetic code, we will be able to deduce the nucleotide changes that the mutagens have caused. Similarly, after isolation and cloning of the Adh-gene from mutant strains, we will carry out DNA sequencing and directly determine the nucleotide changes involved in the mutagenic event.